Toxicity of Insecticides toFrankliniella invasor(Thysanoptera: Thripidae) Under Laboratory Conditions

Mango cv. ‘Ataulfo’ is perhaps the most popular mango produced in Mexico. The presence of high densities of thrips in mango blossoms, mainly the species Frankliniella invasor Sakimura, has been linked to yield decline. Growers spray synthetic insecticides on a regular basis against thrips to reduce their numbers, but no studies on the effectiveness of these insecticides have been conducted. The present study was undertaken with the objective of assessing the toxicity of 4 insecticides commonly used by growers. Commercial formulations of spinosad, imidacloprid, malathion, and α-cypermethrin were evaluated on adults of F. invasor under laboratory conditions. Six concentrations of each insecticide were assessed: 0.1, 1, 10, 100, 1000, and 10,000 ppm. Snap bean pods were submerged into the different concentrations of insecticides, dried on paper towels, and placed in a plastic container with the thrips adults. A completely randomized design with 10 replicates per treatment was performed. Probit analyses revealed that spinosad and α-cypermethrin were the most toxic insecticides for F. invasor with estimated LC50 values of 0.413 and 0.636 ppm, respectively. No significant differences in toxicity were found between imidacloprid (LC50 = 23.013 ppm) and malathion (LC50 = 34.422 ppm). Mortality in control treatments (distilled water) was never higher than 14%. Our study suggests the use of spinosad and α-cypermethrin as the best control for F. invasor. However, these results should be complemented with field evaluations before being recommended to mango growers. El Mango cv. ‘Ataulfo’ es probablemente el mango mas popular de Mexico. La presencia de altas densidades de trips durante la floracion, principalmente de la especie Frankliniella invasor Sakimura, ha sido vinculada a la baja productividad. Los productores asperjan insecticidas sinteticos de forma regular contra los trips para reducir sus poblaciones, pero no se han llevado a cabo estudios sobre la efectividad de esos productos. El presente estudio se llevo a cabo con el objetivo de evaluar la toxicidad de cuatro insecticidas comunmente usados por los productores. Las formulaciones comerciales del espinosad, imidacloprid, malation, and α-cipermetrina fueron evaluados sobre adultos de F. invasor bajo condiciones de laboratorio. Fueron evaluadas seis concentraciones de cada insecticida: 0.1, 1, 10, 100, 1000, y 10,000 ppm. Para la evaluacion fueron utilizados ejotes, los cuales fueron sumergidos en diferentes concentraciones de insecticidas, secados en papel toalla, y colocados en contenedores de plastico con los trips adultos. Se utilizo un diseno completamente al azar con 10 replicas por tratamiento. El analisis Probit revelo que el espinosad y la α-cipermetrina fueron los insecticidas mas toxicos a F. invasor, con CL50 estimadas de 0.413 y 0.636 ppm, respectivamente. No se detectaron diferencias significativas entre imidacloprid (CL50 = 23.013 ppm) y malathion (CL50 = 34.422 ppm). La mortalidad en el control (agua destilada) no fue mas del 14% de los individuos. Nuestro estudio sugiere el uso del espinosad y la α-cypermethrin para el control de F. invasor. Sin embargo, estos resultados deberan ser complementados con pruebas de campo antes de ser recomendados a los productores. View this article in BioOne